The opinion polls have hardened in favour of the President in the last days of the campaign.

The US goes to the polls today with Barack Obama on the brink of an historic re-election. After a brutal campaign in which the Romney and Obama camps have spent an estimated $6bn between them, making this race comfortably the most expensive election in history, the two candidates are separated by just over one per cent in the national opinion polls. However, Obama holds slight leads in most of the key swing states, including the perennial bellwether state of Ohio. Of the states picked up by Obama against John McCain in 2008, Romney holds poll leads in just Indiana and North Carolina, with Florida and Virginia in a dead-heat.

The two candidates have splurged over $700m on television adverts, most of them negative, in the battleground states. Aside from the presidency, the entire House of Representatives, 34 Senators and 11 governors will be decided today. However, after months of intense campaigning, little is expected to change. The Democrats are poised to retain a narrow majority in the Senate, with the Republicans unlikely to pick up the four seats it needs to take control. In Missouri, Republican candidate Todd Aikin, whose comments about "legitimate rape" rarely leading to pregnancy sparked widespread outrage, is However, the huge gains GOP gains on the back of the Tea Party campaign are not expected to be wiped out, with the Democrats set to fall well short of the 25 gains needed to take a majority in the House of Representatives.

The political deadlock that has existed since the Republicans took control of the House in 2010 is set to continue. In truth, US politics is more divided than it has been for a generation. Despite committing a series of media gaffes, the most notorious being a secretly-filmed video of Romney dismissing the "47 per cent of electors who don't pay income tax and won't vote for me", the former Massachusetts governor has remained in contention. In particular, the Romney campaign was energised by a strong performance against a lacklustre Obama in the first Presidential debate on 3 October. However, after recovering in the final two debates. An opinion poll released over the weekend by the Washington Post found that 79 per cent rated Obama's response to Hurricane Sandy, which ripped through north-eastern America last week, as excellent or good. The President has since been bolstered by October's employment statistics showing that 171,000 jobs had been added to the economy.

Even small factors such as the weather - the forecast for Florida promises rain on Tuesday - may come into play as the party machines complete their 'get out the vote' programmes. However, turnout is expected to be up to five per cent lower than the 57 per cent seen in 2008.

Volunteers at the Romney office in St Petersburg maintain an upbeat demeanour, with a chart on the wall showing the numbers from the minority of favourable opinion polls. But the mood is brittle. Canvassers say they are "scared for their country". One lady tells me that "Obama-care forcing everybody to be equal is just wrong", complaining that the new healthcare regime would force Catholic charities to offer abortions and birth control. She says that she and her husband had to sell their home to pay rising medical bills 'but that's how it works" and proudly states that no Congressional Republicans voted for the bill.

The antipathy to their opponents is not reserved to Republicans. Victoria Yeroian, Young Democrats President at Virginia Commonwealth university in Richmond, describes the Tea Party to me as "an organised version of the Ku Klux Klan".

Democrat party operatives in Virginia and Florida have been in full lock-down mode when it comes to speaking to journalists but seem quietly confident amid the bustle of campaigning activity. The opinion polls have hardened in favour of the President in the last few days, and Democrats have been cheered by New York Times's uber-pollster Nate Silver, who projected a comfortable Obama win on Monday night, placing the vital bellwether state of Ohio, along with Florida and Virginia, in the Democrat column. Silver's formula puts a 92 per cent likelihood on Obama being re-elected, estimating that the President will claim between 310-315 electoral college votes.

As ever, attention will focus on the three big swing states - Pennsylvania, Ohio and Florida. No Republican has ever won the keys to the White House without claiming Ohio, but Romney needs to claim the Buckeye State and either Florida or a clutch of smaller swing states. The world is watching as America votes.